Baill mill



May 3 1927.

P. L. snows" BALL MILL Filed Sept. so 1925 3 Sheets-Sheet 1 mmw Wm awa M May P. L. cRowE isALL MILL Filed Sept. so 1925 3 SheetsSheet 2 PauZ 6/ 0 we.

ATTORN BY Mums:

P. L. CROWE May 3 a BALL MILL 3 Sheets-Sheet 3 I Filed Sept. 50 1925 Paw ZZZ. Crawe INVENTOR ATTORNEY Patented May 3, 1927.

UNITED STATES PATENT OFFICE;

PAUL L. CROWE; or BALTIMORE, MARYLAND.

BALL :MILL.

Application filed September 39,4925. SerialNo. 59,541.

Another object is the provision of a mill for this purpose which will supply demands for any condition or capacity.

Another object is the provision of a mill for this purpose which is small in size when compared to the capacity thereof.

Another object is the provision of a mill for this purpose which may be arranged in any position that may be available and yet properly supply the demand for its heating capacity. I

Another object is the provision of a mill of this character which is quick and effective in operation.

With these objects in view and others which will be apparent as the description progresses, the improvement resides in certain other novel constructions, combination and novel association of parts hereinafter.

Figure 5 is a central longitudinal sectional view through another and larger form of the improvement.

Figure 6 is a sectional view on the line 66 of Figure 5.

Figure 7 is a sectional view on the line 7-7 of Figure 5.

Figure 8 is a sectional View on the line 8-8 of Figure 5.

Figure 9 is a sectional view on theline 99 of Figure 5. I

Figure 10 is a sectional View on theline 1 O10 of Figure 5.

Figure 11 is a sectional view on theline 11 -11 of Figure 5. a r

Figure 12 is a plan view of one of the .segments employed in the construction of the screen.

Figure 13 is a sectional viewon the line 13--13 of Figure 12.

Figure 14; is a plan view of one of the segments from which the drum is constructed.

. Flgure 15 is a sectional view on the line 1515 of Figure 14. r

Figure 16 is a transverse sectional view through the body portion of a modified form of the mill.

My improvement consistsin a pulverizing and blowing apparatus in which is combined centrifugally for impelling and grinding material by impulsive impact and feed ing the same into acombustion chamber as fuel, or the introduction of pulverized coal into furnaces for its combustion in sucha manner as to produce an effective, convenient, durable and commercial machine which comprises a furnace feeding mechanism em bodying a blowing impeller having bearings upon which it revolves, in company with ball mills and hollow shafts, the said bearings.-

having their supports extended in any conventional and convenient setting or base.

The action of the process and method is centrifugal by the. employment of an impeller and powerbehind it with the use of small steel balls and flint pebbles manufactured for the reduction of material to be ground. As this process continues the coal is fed evenly in fine particles suifioiently ground to pass through a 95 per cent screen mesh while a flow of air carries the ground fuel through the screen mesh into the impellerandis in turn forced by the impeller intothe feedingtube and .from thence into the furnace- As the "fuel particles are 'reduced in size in the mill compartment. by the abrasion of the balls and pebbles, the weightand speed of, or turning movement of the apparatus and mill compartment or chamber, the fuel is effectively reduced to a fineness best suited for the combustion thereof.

The mill chambers or compartments may be supplied to comply with the requirements of the consumer, or manufacturing plant, for quantities, capacities and for dryness of the fuel to the degree of combustion requirements,

In the drawings the numeral 1 designates suitable supports upon which appropriate bearings 2are mounted. The numeral 3 designates the impelling cylinder and the numeral 4 the grinding chamber. The cylinders 3 and t are centrally located. side by side between the bearings 2 and have hollow central portions in the nature of shafts 5 located in the bearings. The hollow shafts constitute the delivery or outlet of the combustible flow, and to one of the hollow shafts 5 a delivery tube 6 is secured. At the opposite side of the mill there is located the coal feeding hopper 7, the same having attached thereto an air flow tube 8. The hopper and the flow tube are so constructed as to partly encircle the upper portion of one of the bearings 2. The material when placed in the hopper flows downward into the compartment 4 above the tube 8 and when the mill is in operation air is induced through the tube 8 and the material is forced through the tube 6, but when the direction of the mill is reversed the air is drawn through the tube 6 and forced through the tube 8. Thus it will be noted that the mill can be operated in either direction which induces the air and forces the combustible material from one to either side of the mill. The lower end 9 of the hopper 7 is secured to the supporting base 1 by a cap screw 9, and the tube 6, or any burner, conventional or special, may be used either attached directly to the mill or at a distance away from the mill if required.

As shown in Figures 2 and 3 of the drawings, the bearing cap and supporting base are secured to each other by the usual bolts 10, while in the larger mills, hereinafter referred to the bearings are preferably constructed flatwise, the purpose of which will later appear.

The central partition 11 divides the impeller from the mill chamber, the impeller 3 having fan blades 12 adapted for induction from the hopper side of the mill and force the combustible material from the adjoining mill chamber to the outlet 6, although this direction may be reversed providing the blades of the impeller are reversely directed. Also if desired, the chamber 4t may be provided with fan blades. The mill chamber 4 is partly filled with impact, attrition balls and pebbles 13 of all sizes and by the reduction of the fuel in turning the accompanying chamber by the impeller at the speed required, the attrition elements reduce the fuel to the required fineness for their passage through thcpartiition screen ll. The mesh of the screen 11 is from to 98 per cent of and this required fineness allows the passage or flight of the fuel through the said partition screen into the impeller by pressure caused in the momentum of the impeller aided by the attrition elements, the said fuel, at the same time, being well mixed for the combustion thereof by air currents induced through the tube 8. The amountof pressure is regulated by a damper 14 in the said tube 8.

The casing constituting the chambers 3 and l may be connected together in any dc sired manner, and the fan 12 may have its blades integrally formed with the: outer or side wall of the chamber 3.

In Figure l of the drawings there illustrated a pipe 15 which has an offset or nozzle end received in the hopper 7 and opposite end connected to the furnace, lining from which the induction of the air pr sure in the impeller draws suiiicient warm air to raise the temperature of th mill to the degree required for the proper drying and combustion of the pulverized fuel.

The tube 6 may be directly connected to a conductor tube or burner 16 (Figure l) or the said tube may have connected thereto a extension for the connection of one or more additional burners.

A longitudinal sectional view through larger mill is disclosed by Figure 5 of the drawings and comprises and consists in the same elements and construction and cooperzn tion as that shown in the mill just descril'ied. The mill comprises two compartments and, therefore, is in the nature of a twin mill for supplying combustible material to a num ber of furnaces and boilers and, of course. employs a number of pulverizing units for various purposes, permitting various burners to be placed in use or shut off without interfering with those in operation.

By referring to Figure 5 and the elements disclosed in other views forming part of the construction, it will be noted that the parts are assembled for repairing and facilitat ing in the performance of the repairs and that one end of the mill may be operated without the other end and that one motor can operate both mills. The hearings on the support for the mill previously illustrated are in the nature of balls, but the bearings for the mill disclosed in Figure 5 may be in the nature of rounded bushings or balls, the supporting frame 1 being straight or flat at the bearing portion thereof. lhe mill chambers are indicated by the numerals 4t, and the impelling chambers by the numerals 3. The screen partition 17 is made up of apertured segments havingthe opposite faces the ends thereof reduced to form tongues, the tongue of one segment being arranged in lapping engagement with respect to the tongue of the cooperating sec- 'tion and these tongues are bolted together so that the screen partitions are in the forms of hollow shafts. The screen segments are of the hardest iron or steel and each of the hollow shafts l? is mounted on a hollow shaft 5, the said shaft having star ribs 5% which hold the hollow shaft 17 spaced therefrom. The chambers 4 have their outer walls also preferably constructed of nonreticulated segments having lapping ed torwhich are bolted together, (F igure 8). The inner ends or heads of each of the mill chambers 4 are concaved inwardly and provided Ill) lift) with paced openings 20 (Figure 7), while the outer-heads are hollow and provide the-- The concaved 'inner' impelling chambers. heads 20 permit of access beingobtained to the inner and removable section 21 of the hollow shaft The central bearing 1 of the frame is extended to provide'a hopper:

22 and this hopper is divided by a partition 23 into two compartmentsthat communicate with the respective mills 4:. Preferably,

' iron plates 24, whose edges overlap and are respectively.

secured together by any suitable effective means. The portion of the hollow shaft 5 received in the impelling chambers has anoutstanding disc flange 25 on whose opposite faces there are secured fan blades 26 and 27, The spaces between the fan blades 27 communicate with the hollow shaft.

The closed ends of the hollow shafts in the end bearings have thereon poles for the generator, which will hereinafter be referred for burner tubes, while communicating with right angular openings the bearings for the said hollow shaft'have angle openings inv which are screwed extension tubes 6 for similar burners.

As the coal is introduced into the hoppers its course is through the openings 20 in the inner heads 20' of the mills where the same is acted upon by the attrition balls 30. The pulverizing is effected by the attrition balls and the turning movement of the impellers 26 and 27 and the compartment walls 24, the operation being exactly similar to that set forth in connection with the description of Figure 1, the difference only being that the construction disclosed in Figure 1 is narrow and that in Figure 5 is wide or longer,

,the atmospheric air being drawn into the mill in the exact manner as that previously described, and heated air is likewise introduced into the mill through pipes 31 that are connected to a suitable source of heat and have nozzle ends in the respective compartments in the hopper 22. It is obvious that coal may be introduced into one of the mills and ground thereinwhen both of the mills are revolved and likewise that one of the mills may be disassociated from the other when only one mill is required for opera tion. This construction is illustrated to show the manner in which my mills may be manufactured to suit or comply with differ ent conditions.

Any suitable motive power may be employed for driving my improved pulverizing ball mills, the same being preferably, however, driven by electricity produced by induction in a motor generating set. The pole pieces 32 for the motor to operate the mill may be located at any convenient face These closed ends of the shafts may be 'of ithe body portion'of the mill which is most available and suitable for the motor application. 'Inthe showing of the drawings the pole pieces are located as near'thecenter of rotation of the mill aspossible and convenient: for their operation. Astheimotor operates the mill it also causes the generator to generate to the limit of the dis tame. the motor is located from the, generator centrally or from the generator to the motor. peripherally. .Thus itwill be seen and understood that the power current will be controlled so that the supply of the power current will be permitted to supply only the amount necessaryto keep. up the speed to its required degree of rotation and load and thus, in other words, the power current will be regulated in quantity .to only the amount necessary between the current needed by the motor which is not supplied by the genera tor. vIt will be also understood that. although some impeller 'and ball. mills are small, others may be larger in diameter and sufficiently contracted in width to curtail the use of the power current, both as to a ball mill and its impeller for the application of the principle involved in this application and use of power generally as applied to va rious constructions of appliances in general.

The application of the motor generator set consists in a ring or disc 33 on which the pole pieces 32 are arranged. .The disc or ring 33 maybe used as a rotor or starter core or. disc for the respective windings and the ringer disc may be located over either one or both of the chamber peripheries, closing the chambers ofthe mills, or for other purposes, such as forcing or inducing the air from or to the compartments in the mill.

In Figure 16 the construction is substantially similar to that disclosed in Figure 1, except that impeller blades are arranged in both the ball and impelling compartments and one of the compartments is surrounded by a ring on which are arranged the pole pieces for the induction motor, a screen 34 dividing the compartments and the center and closed faces of the compartments are formed with hollow shaft extensions 35.

The closure for the end bearings in the construction disclosed in Figure 5 are removable so that access may be obtained to the hollow shafts and to the impeller chamhers. I

Both sizes of the pulverizing and feeding ball mills are constructed and designed to facilitate the dismantling of the said mills for repairs and are also designed to show the variable constructions invloving the process and method as well as the wide range of the intermediate constructions, both having the same principle in operation, in manufacture. Also in both constructions I seek to obtain economy in manufacture, in installations, in power, in fuel, in current,

in space and in application. The material for use in-tl1e various parts of the apparatus, is and will be varied to the requirements of the particular parts themselves.

The pole pieces of the construction illustrated in Figure 6 may be arranged at the center or at either side of the center of the mill.

The improvement is necessarily susceptible to changes in form, material employed, and in details of construction, and therefore the improvement is to be limited only to the scope of the appended claims.

Having described the invention, I claim 1. A means for pulverizing coal or other fuel, comprising a hollow body having hollow shafts on the sides thereof, bearings for the shafts, said body being divided by a screen into compartments, impeller blades in said compartments, attrition balls in one of said compartments, means for delivering fuel into said compartment, a hot air and an atmospheric air pipe communicating with the last mentioned compartment, and a burner tube connected to the hollow shaft of the adjacent compartment, all as and for the purpose set forth.

2. A motor driven mill for pulverizing coal or like combustible material, having its ends provided with outwardly directed hollow shafts, bearings for the shafts, a removable hopper on one side of the mill com municating therewith, a hot air conducting pipe having a nozzle end received in the hopper, an atmospheric conducting pipe connected with the hopper and communicating with the mill, a damper controlling the passage through said pipe, said mill divided by a partition int-o compartments, attrition balls in the compartments adjacent the hopper, a fan blade impeller in the second com-- partment, and a burner tube connected to the shaft of the impeller compartment, all

and for the purpose set forth.

3. A ball mill for pulverizing coal or like fuel, and for feeding said pulverized coal into burner nozzles, comprising a hollow mill body, a hollow shaft for the body, bearings for the shaft, said body being made up of segmental plates and having an inner lining, a screen in the body, said screen being made up of segmental sections which are bolted together, means supporting the screen in spaced relation with respectto the hollow shaft, an impeller chamber in the mill, with which the screen communicates, oppositely directed fan blades in the impeller chamber and a partition therebetween, attrition balls in the mill chamber, a hopper for introducing the material into the mill chamber, means for revolving the mill chamber to subject the material to centrifugal action and pounding action of the attrition balls, and said impellers creating a draft of both heated and atmospheric air in the mill chamber'to assist in forcing the powdered material through the screen and successively against the blades of the impeller, to permit of the latter introducing the powdered material into the hollow shaft and through burner tubes which communicate with said shaft.

In testimony whereof I afiix my signature.

PAUL L. CRO "VE. 

